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Talk:Sun Rise and Set
Considering the mountainous structure of the region, what height are these times calculated for? If it is sea-level (which seems reasonable), we should get sunrise a little earlier on top of the mynd and a little later in the valleys? --SamuelUser talk:Samuel 12:43, 14 January 2007 (UTC) ::It is sea level - but simple calculations that work out the differences for altitude tend to work on an observer at an altitude above sea level calculating revised times based on a horizon at sea level. Here the horizon in most directions is at a comparable altitude to the observation point. ::My thoughts in posting it was more to give a feel - to get an idea of the times between set & rise at different times - rather than to give definitive times. --OldNick 16:12, 15 January 2007 (UTC) ---- An interesting FAQ regarding time. http://sciastro.astronomy.net/sci.astro.3.FAQ It also talks about 'green flash', a phenomenom that can be observed at sunset and sunrise, especially from mountains. Here are four data sets for comparison (1220-3-1, 1220-6-1, 1220-9-1 and 1220-12-1.) I am not sure if the original set was calculated with an online calculator that is tolerant of pre-1901 dates, but the times are so close that it doesn't matter. This calculator can be found at: http://www.sci.fi/~benefon/sol.html and is not compatible with Firefox. The Civil Twilight data is probably the most useful new data here. The calculator can be readily abused in order to work out which day of the week it was in 1220, etc. Daylength: 10:53 hours Begin of Nautical Twilight: 05:44 hours Begin of Civil Twilight: 06:23 hours Sunrise Time: 06:58 hours Sunset Time: 17:51 hours End of Civil Twilight: 18:26 hours End of Nautical Twilight: 19:05 hours Max. height angle is 30:06 degr at noon time 12:25 Declination of Sun: -7:21 degr Sun altitude -44:16 degr, azimuth 11:58 degr (UTC 00:00) Solar power 557 W/m2 at noon Date: Sunday on 1220-03-1, the 61. day of the year Location: input, latitude 52:33, longitude -2:52 Daylength: 16:31 hours Begin of Nautical Twilight: 01:50 hours Begin of Civil Twilight: 03:04 hours Sunrise Time: 03:52 hours Sunset Time: 20:23 hours End of Civil Twilight: 21:11 hours End of Nautical Twilight: 22:25 hours Max. height angle is 59:37 degr at noon time 12:08 Declination of Sun: 22:10 degr Sun altitude -14:39 degr, azimuth 10:35 degr (UTC 00:00) Solar power 1046 W/m2 at noon Date: Monday on 1220-06-1, the 153. day of the year Location: input, latitude 52:33, longitude -2:52 Daylength: 13:38 hours Begin of Nautical Twilight: 04:02 hours Begin of Civil Twilight: 04:46 hours Sunrise Time: 05:22 hours Sunset Time: 19:00 hours End of Civil Twilight: 19:36 hours End of Nautical Twilight: 20:20 hours Max. height angle is 45:40 degr at noon time 12:11 Declination of Sun: 8:13 degr Sun altitude -28:38 degr, azimuth 11:20 degr (UTC 00:00) Solar power 846 W/m2 at noon Date: Tuesday on 1220-09-1, the 245. day of the year Location: input, latitude 52:33, longitude -2:52 Daylength: 07:58 hours Begin of Nautical Twilight: 06:39 hours Begin of Civil Twilight: 07:23 hours Sunrise Time: 08:03 hours Sunset Time: 16:01 hours End of Civil Twilight: 16:42 hours End of Nautical Twilight: 17:26 hours Max. height angle is 15:24 degr at noon time 12:02 Declination of Sun: -22:03 degr Sun altitude -58:41 degr, azimuth 16:31 degr (UTC 00:00) Solar power 245 W/m2 at noon Date: Tuesday on 1220-12-1, the 336. day of the year Location: input, latitude 52:33, longitude -2:52 --James 15:01, 15 January 2007 (UTC)